MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 336

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

9.5.9 Storage Reservation
MPC555
USER’S MANUAL
The MPC555 / MPC556 storage reservation protocol supports a multi-level bus struc-
ture. For each local bus, storage reservation is handled by the local reservation logic.
The protocol tries to optimize reservation cancellation such that a PowerPC processor
is notified of storage reservation loss on a remote bus only when it has issued a stwcx
cycle to that address. That is, the reservation loss indication comes as part of the
stwcx cycle. This method avoids the need to have very fast storage reservation loss
indication signals routed from every remote bus to every PowerPC master.
The storage reservation protocol makes the following assumptions:
CLKOUT
RD/WR
TSIZ[0:1]
TS
Data
TA, BI, TEA
ADDR[0:31]
• Each processor has, at most, one reservation flag
• lwarx sets the reservation flag
• lwarx by the same processor clears the reservation flag related to a previous
• stwcx by the same processor clears the reservation flag
• Store by the same processor does not clear the reservation flag
• Some other processor (or other mechanism) store to the same address as an ex-
• In case the storage reservation is lost, it is guaranteed that stwcx will not modify
/
lwarx instruction and again sets the reservation flag
isting reservation clears the reservation flag
the storage
MPC556
Figure 9-28 Termination Signals Protocol Timing Diagram
acknowledge signals
allowed to drive
Slave 1
Slave 1
EXTERNAL BUS INTERFACE
Rev. 15 October 2000
negates acknowledge
signals and turns off
Slave 1
acknowledge signals
Slave 2
allowed to drive
Slave 2
Slave 2
negates acknowledge
signals and turns off
MOTOROLA
9-40